ABG Academy + Drug Math
Start with simple acid–base patterns, work up to mixed disorders, or switch to medication calculations. All questions are randomized and explained after grading.
Beginner — four basic disorders
No mixed cases · compensation made simple · no PaO₂Choose your interpretation
In beginner mode, use the simplified NCLEX classroom convention; real compensation is more precise than these three labels.
Quick-reference guide
↑ PaCO₂ → ↓ pH
Think hypoventilation/CO₂ retention.
↓ PaCO₂ → ↑ pH
Think hyperventilation/CO₂ loss.
↓ HCO₃⁻ → ↓ pH
Think loss of base / gain of acid.
↑ HCO₃⁻ → ↑ pH
Think excess base / acid loss.
Compensation explained
Uncompensated (classroom shorthand): secondary value has not visibly moved to oppose the primary pH change. Partial: secondary value changes appropriately but pH remains outside 7.35–7.45. Compensated: pH is within its reference range despite a primary disorder. In real patients, expected compensation must be calculated; an apparently normal pH can hide two primary disorders.
Expected compensation (Intermediate / Advanced)
Metabolic acidosis: Winter’s predicted PaCO₂ ≈ 1.5 × HCO₃⁻ + 8 (±2). Metabolic alkalosis: expected PaCO₂ ≈ 40 + 0.7 × (HCO₃⁻ − 24) (rough estimate). Acute respiratory acidosis: HCO₃⁻ rises ~1 mEq/L for each 10 mmHg CO₂ rise; chronic ~3–4. Acute respiratory alkalosis: HCO₃⁻ falls ~2 per 10 mmHg CO₂ drop; chronic ~4–5. A response outside expectations suggests mixed disease.
Why PaO₂ is Advanced-only
PaO₂ measures oxygenation, not whether the primary acid–base problem is respiratory or metabolic. A low PaO₂ can coexist with any of these patterns. PaO₂ interpretation depends on age, FiO₂, altitude, and clinical context; the examples assume room air and a sea-level setting.
Drug Math — calculator + practice
Select the type of nursing calculation, enter labeled values, and see the working. The practice section creates new math problems without asking you to use real patient data.
Calculator
Units shown at every stepRandom drug math practice
A new question uses the calculation selected above. Practice values are fictional arithmetic examples, not prescribing recommendations.
Reference material: Merck Manual: primary changes and compensation; American Thoracic Society: ABG interpretation. Not endorsed by these organizations. †Typical adult PaO₂ at sea level on room air; contextual interpretation required.